In magnetic disk drives such as hard disk drives (HDDs), the following method has been used: a CSS (Contact Start and Stop) method in which a magnetic head is kept in contact with a contact sliding zone (CSS zone) located in an inner region of a face of a magnetic disk during halt, the magnetic head is slid on the CSS zone and then lifted therefrom during startup operation, and data is then recorded on or reproduced from a recording/reproducing zone located outside the CSS zone. The magnetic head is moved from the recording/reproducing zone onto the CSS zone, slid on the CSS zone, and then stopped during shutdown operation. In the CSS method, startup operation and shutdown operation, during which contacting/sliding takes place, are referred to as CSS operation.
CSS-type magnetic disks need to have both CSS zones and recording/reproducing zones arranged in faces thereof. Furthermore, the magnetic disks need to have surface irregularities with a certain roughness such that magnetic heads are not stuck to the magnetic disks when the magnetic heads are brought into contact with the magnetic disks.
Japanese Unexamined Patent Application Publication (JP-A) No. 62-66417 (Patent Document 1) or the like discloses a magnetic recording medium coated with a perfluoroalkylpolyether, having the formula HOCH2—CF2O—(C2F4O)p—(CF2O)q—CH2OH, useful in reducing the damage on occurrence of contacting/sliding between a magnetic head and a magnetic disk during CSS operation.
Japanese Unexamined Patent Application Publication (JP-A) No. 9-282642 (Patent Document 2) and Japanese Unexamined Patent Application Publication (JP-A) No. 10-143838 (Patent Document 3) disclose magnetic recording media with high CSS durability. Furthermore, Japanese Unexamined Patent Application Publication (JP-A) No. 2001-164279 (Patent Document 4) discloses a magnetic recording medium having good sliding properties and high CSS durability due to a lubricant purified by a supercritical extraction method.    Patent Document 1: Japanese Unexamined Patent Application Publication (JP-A) No. 62-66417    Patent Document 2: Japanese Unexamined Patent Application Publication (JP-A) No. 9-282642    Patent Document 3: Japanese Unexamined Patent Application Publication (JP-A) No. 10-143838    Patent Document 4: Japanese Unexamined Patent Application Publication (JP-A) No. 2001-164279